Unless
you want to risk a legal problems, you should avoid graphics that you
did not create or that are not freely distributed. We'll point you to
some great resources that'll give you all the legitimate graphics you
could want or need.

Because
different browsers can work in strange ways, you should verify that your
website works with each of the major browsers - or else risk some unhappy
visitors, especially if you're using Javascript or advanced HTML. Don't
simply try the latest versions either because many of your visitors are
likely using earlier, less-capable browsers.